Fuel cell system

ABSTRACT

As the fuel cell apparatus of the present invention comprises a fuel cell for generating electricity by supplying a fuel pole with fuel gas and an oxidant pole with air, a washing liquid tank, disposed in a supply passage of the air, for reserving washing liquid, and a means for replacing the washing liquid reserved in said washing liquid tank, can supply the oxidant pole with air washed with the washing liquid, and replace the washing liquid periodically, allowing to supply the oxidant pole with always clean air. As it can supply the oxidant pole with clean reaction air not containing dust of inorganic or organic substance, volatile components of aromatics or paints, CO, NOx, SOx, cyanides, sulfates, aromatic compounds, ammonium or the other harmful substances exerting bad effects on the cell characteristics and prevent the alteration of electrolyte based on the chemical reaction between harmful substance and electrolyte, the reliability is high, the life is long life and the durability is high.

FIELD OF THE INVENTION

The present invention concerns a fuel cell apparatus, and moreparticularly a fuel cell apparatus allowing to supply a reaction airfree from a trace of harmful substance contained in the reaction air.

BACKGROUND ART

An example of conventional fuel cell system is shown in FIG. 6. In thesystem, a desulfurizer 2 is supplied with a raw fuel 1 such as naturalgas, town gas, methanol, LPG, butane or the like, and here the raw fuelis desulfurized. The raw material having passed through the desulfurizeris pressurized by a pressure pump 10, and supplied to a reformer 3, togenerate a reformed gas containing hydrogen, carbon dioxide and carbonmonoxide. The gas having passed through the reformer 3 is supplied to aCO transformer 4 and, here, carbon monoxide contained in the reformedgas is transformed into carbon dioxide. The gas having passed throughthe CO transformer 4 is supplied to a CO remover 5 and, here, nontransformed carbon monoxide contained in the gas having passed throughthe CO transformer 4 is removed.

Hydrogen rich reformed gas after the removal of carbon monoxide havingpassed through the CO remover 5 is supplied to a fuel cell 6. The fuelcell 6 comprises a fuel pole 6 a, an oxidizer pole 6 b and a coolingportion 6 c and the aforementioned hydrogen is supplied to the fuel pole6 a. The hydrogen reacts with oxygen contained in the air supplied intoa water tank 21 through a fan 11, humidified and then supplied to theoxidizer pole 6 b, generating electricity.

For instance, when the fuel cell 6 uses a solid polymer electrolytefilm, the solid polymer electrolyte film is humidified with moisturecontained in the humidified air supplied to the oxidant pole 6 b, forimproving the ion electric conductivity.

The reformer 3 includes a burner 12 which is supplied with raw fuelthrough a pipe 13, supplied with air through a fan. 14 and supplied withnon reacted hydrogen having passed the fuel pole 6 a, through the pipe15. When the system is started, the burner 12 is supplied with raw fuelthrough the pipe 13 and, at the same time, supplied with air through thefan 14 and, after the start, in case where the system stabilizes, theraw fuel supply is cut and the burner 12 is supplied with non reactedhydrogen having passed the fuel pole 6 a, through the pipe 15.

Chemical reactions having a predetermined reaction temperature takeplace in the aforementioned reformer 3, CO transformer 4, CO remover 5and fuel cell 6. The chemical reaction in the reformer 3 beingendothermic, the chemical reaction is performed all the way heating withthe burner 12.

The chemical reaction taking place in the CO transformer 4 and COremover 5 being exothermic, for instance in the CO remover 5, combustiongas is generated by burning a not shown burner only during the systemstart, the temperature of the CO remover 5 is heated to the reactiontemperature by the heat of the combustion gas generated at this moment,and during the operation, it is cooled so that the temperature does notelevated to the reaction temperature or higher by the heat of theexothermic reaction.

Each heat exchanger 18, 19 and 20 is connected respectively between theaforementioned reformer 3 and CO transformer 4, between CO transformer 4and CO remover 5, and between CO remover 5 and fuel cell 6.

Water from a water tank 21 circulates through respective heat exchangers18, 19, 20 through pumps 23, 24, 25 and the gas having passed throughthe reformer 3, CO transformer 4, CO remover 5 is cooled respectively bythese waters.

Water from the water tank 21 circulates through the cooler section 6 cof the fuel cell 6 through a pump 48, and the fuel cell 6 is cooled withthe water. 26 indicates an exhaust system of the oxidant pole 6 b of thefuel cell 6.

A heat exchanger 17 is connected to an exhaust system 31 of theaforementioned reformer 3, and when the water of the water tank 21 issupplied through a pump 22, it becomes moisture vapor in the heatexchanger 17, and the moisture vapor is mixed with the raw material andsupplied to the reformer 3.

In the aforementioned conventional system S, air (the atmosphere air)around the fuel cell is supplied to the water tank 21 through the fan11, humidified and supplied to the oxidant pole 6 b as reaction air.Consequently, a trace of NOx, SOx, cyanides, sulfates, aromatics,ammonium, organic solvents or the other impurities exerting bad effectson the cell characteristics contained in the air (the atmosphere air) isonce removed by the water reserved in the water tank 21. However, whenthe operation time is prolonged, the concentration of impurities in thewater increases, and impurities in the air passing through the watertank 21 are not removed no more, for supplying the oxidant pole 6 withair containing impurities as reaction air.

The aforementioned impurities contained in the reaction air arrive atthe electrode catalyst layer permeating through the electrode mediumwith oxygen in the air, come into contact with the electrolyte andprovoke a chemical reaction, and the chemical reaction alter theelectrolyte and deteriorate functions as electrolyte and, at the sametime, inhibit the oxygen absorbing function of the electrode catalyst,and these causes provoke problems such as deterioration of cellcharacteristics or life characteristics of the fuel cell.

Besides, problems of bad effects due to the impurities contained in suchreaction air were not limited to a fuel cell using the solid polymerelectrolyte film, but encountered similarly in the other fuel cells suchas phosphoric acid type fuel cell.

The present invention has an object of solving conventional problems,preventing cell characteristics and life characteristics of a fuel cellfrom lowering by composing to supply the oxidant pole 6 b of the fuelcell 6 with reaction air, preliminarily removing a trace of inorganicand organic dust, aromatics, volatile components of paint, CO, NOx, SOx,cyanides, sulfates, aromatic compounds, ammonium or the other harmfulsubstances exerting bad effects on the cell characteristics contained inthe air (the atmosphere air), and providing a fuel cell apparatus ofhigh reliability, long life and high durability.

DISCLOSURE OF THE INVENTION

In order to solve the aforementioned problem, the fuel cell apparatus ischaracterized by comprising a fuel cell for generating electricity bysupplying a fuel pole with fuel gas and an oxidant pole with air, awashing liquid tank, disposed in a supply passage of the air, forreserving washing liquid, and a means for replacing the washing liquidreserved in the washing liquid tank.

The oxidant pole can be supplied with always clean air by supplying theoxidant pole with air washed with the washing liquid in the washingliquid tank, disposed in the air supply passage, and by replacingwashing liquid.

The fuel cell apparatus is the fuel cell apparatus wherein the washingliquid is water, or a washing liquid of organic compound.

The use of water or washing liquid of organic compound as washing liquidallows to remove impurities in the air.

The fuel cell apparatus is the fuel cell apparatus wherein the washingliquid tanks are disposed in plurality in series on the air supplypassage, and comprise a means for replacing periodically at leastwashing liquid reserved in a washing liquid tank arranged upstream.

The use of a plurality of stages of washing liquid tank for cleaning theair allows to plan a further air purification. Particularly, acombination of a washing liquid tank using water and a washing liquidtank using washing liquid of organic compound allows to remove a varietyof impurities. In addition, in case of using such a plurality of stagesof washing liquid tank, the replacement of washing liquid is effectiveonly by executing at least for the washing liquid tank arrangedupstream.

The fuel cell apparatus is the fuel cell apparatus wherein a pluralityof washing liquid tanks reserving the same washing liquid are disposeddifferently from each other in the liquid level, and a lower washingliquid tank is supplied with washing liquid from an upper washing liquidtank by the level difference.

The level difference of both tanks allows to supply easily the lowerwashing liquid tank with water from the upper washing liquid tank.

The fuel cell apparatus is the fuel cell apparatus wherein the water tobe supplied to a washing liquid tank using water as washing liquid, is awater treated water.

The water to be supplied to the washing liquid tank is preferably awater from which dust or the other impurities are removed by the watertreatment and further, a water from which harmful substances exertingbad effects to the cell characteristics are eliminated is morepreferably, and particularly, a pure water obtained by the watertreatment is preferably.

The fuel cell apparatus of is characterized by comprising a fuel cellfor generating electricity by supplying a fuel pole with fuel gas and anoxidant pole with air, a water tank for reserving cooling water of thefuel cell, a washing liquid tank, disposed in a supply passage of theair, for reserving washing liquid, and a means for replacing the washingliquid reserved in the washing liquid tank.

The fuel cell apparatus is the fuel cell apparatus wherein the means forreplacing washing liquid is operated every fixed time.

The fuel cell apparatus is the fuel cell apparatus wherein the means forreplacing washing liquid is operated according to the dirtiness ofwashing liquid.

The fuel cell apparatus is the fuel cell apparatus comprising a meansfor supplying the washing tank with water of the watertank.

The fuel cell apparatus is the fuel cell apparatus wherein the air issupplied to the oxidant pole, after impurities in the air in the washingliquid tank is removed, and the air is humidified in the water tank.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a composition diagram showing a first embodiment of the fuelcell apparatus of the present invention.

FIG. 2 is a composition diagram showing a second embodiment of the fuelcell apparatus of the present invention.

FIG. 3 is a composition diagram showing a third embodiment of the fuelcell apparatus of the present invention.

FIG. 4 is a composition diagram showing a fourth embodiment of the fuelcell apparatus of the present invention.

FIG. 5 is a composition diagram showing a fifth embodiment of the fuelcell apparatus of the present invention. In FIG. 1 to FIG. 5, the samecomponents as the related art showing FIG. 6 are indicated by the samereference for omitting a duplicate description.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, embodiments of the present invention will be described in detailreferring to drawings.

In a system S1 of a fuel cell apparatus shown in FIG. 1, a fuel cell 6comprises a reaction air washing means 27A for removing harmfulsubstances in the reaction air by washing with water.

The reaction air washing means 27A comprises a washing liquid tank 27containing water for washing, a water supply passage 28 for supplying awashing liquid tank 27 with water obtained by treating city water by awater treatment apparatus 37, an air supply passage 31 for taking air(the atmosphere air) by a pump 30 through a filter 29 and supplying tothe washing liquid tank 27, a washing air supply passage 32 forsupplying a water tank (washing liquid tank reserving water as washingliquid. Called water tank, hereinafter) 21 for humidifying an air fromwhich harmful substances are removed by washing the air with water aswashing liquid in the washing liquid tank 27, and a discharge means 34for discharging periodically water as washing liquid contained in thewashing liquid tank 27.

The means 34 for discharging periodically water comprises a dischargepassage 35 and an on-off valve 36, for discharge, installed on thedischarge passage 35.

38 is a passage for supplying the water tank 21 with water obtained bytreating city water by the water treatment apparatus 37, and LC/1 is alevel controller installed in the water tank 21 for opening/closing theon-off valve 39 installed on the passage 38 so as to maintain the levelof water contained in the water tank 21 to a predetermined level.

LC/2 is a level controller installed in the washing tank 27 foropening/closing an on-off valve 33 installed on the water supply passage28 so as to maintain the level of water for washing contained in thewashing water tank 27 to a predetermined level.

When the system S1 of the fuel cell apparatus of the aforementionedconfiguration is operated, the water tank 21 and the washing liquid tank27 respectively are supplied with a predetermined quantity of water (forinstance, pure water) obtained by treating city water by the watertreatment apparatus 37 through the passage 38 and the water supplypassage 28.

On the other hand, air (the atmosphere air) taken in by the pump 30 andfrom which dusts or the like are remove through the filter 29 issupplied to the washing liquid tank 27 through the air supply passage31. Then, the water supplied to the washing liquid tank 27 is made intocontact, mixed and washed sufficiently with the water for washingcontained in the washing liquid tank 27 for removing harmful substances.

Thus, the air from which a trace of NOx, SOx, cyanides, sulfates,aromatics, ammonium or the other harmful substances exerting bad effectson the cell characteristics contained in the air is eliminated issupplied to the water tank 21 through the washing air supply passage 32to be humidified. The air humidified in the water tank 21 is supplied tothe oxidant pole 6 b of the fuel cell 6 as reaction air. As it is soconfigured to supply the oxidant pole 6 b of the fuel cell 6 with aclean reaction air free from harmful substance, the alteration ofelectrolyte based on the chemical reaction between harmful substance andelectrolyte, and the decrease of oxygen absorbing ability of theelectrode catalyst can be prevented, and the decrease of cellcharacteristics caused by them can be avoided.

Water contained in the washing liquid tank 27 used for removing harmfulsubstances by washing the air is discharged periodically (for instance,according to a calendar day and hour, or when the power generationattains a predetermined value, or when the power generation time attainsa predetermined value, or when the system operation time attains apredetermined value, or when the dirt detected by an electricconductivity sensor or the like becomes equal or superior to apredetermined value) by opening the on-off valve 36 automatically ormanually.

As it is so configured to supply the washing liquid tank 27 with freshwater, after the discharge, harmful substances can be removed alwayscontinuously and easily in the washing liquid tank 27, and the aircontaining harmful substance is limited and prevented from beingsupplied to the oxidant pole 6 b of the fuel cell 6 through the watertank 21.

FIG. 2 is a composition diagram showing a second embodiment of the fuelcell apparatus of the present invention.

In a system S2 of a fuel cell apparatus, a fuel cell 6 comprises areaction air washing means 27B for removing harmful substances in thereaction air by washing with water. The reaction air washing means 27Bis similar to the reaction air washing means 27A of the system S1 of thefuel cell apparatus shown in FIG. 1, except that the washing liquid tank27-1 is installed lower than the water tank 21 so that the washingliquid tank 27-1 is supplied with water from the water tank 21 by thelevel difference H between both tanks.

Consequently, the reaction air washing means 27B has the same functionaleffects as the reaction air washing means 27A of the system S1 of thefuel cell apparatus shown in FIG. 1 and moreover, as the washing liquidtank 27-1 is installed lower than the water tank 21, the washing liquidtank 27-1 can be supplied with water from the water tank 21 by the leveldifference H between both tanks.

FIG. 3 is a composition diagram showing a third embodiment of the fuelcell apparatus of the present invention. The fuel cell 6 in the systemS3 of the fuel cell apparatus comprises a reaction air washing means 27Cfor removing harmful substance in the reaction air by washing withwashing liquid other than water.

Washing liquids other than water used in the present invention are notparticularly limited; however, to be more specific, organic compoundssuch as hydrocarbons, alcohols or the like can be cited, and as washingliquid that can wash and remove well NOx, SOx or the like, for example,washing liquid obtained by dissolving sodium tungstate or molybdate inwater or organic medium and adding as necessary urea aldehyde to thesame or the others can be cited.

The reaction air washing means 27C is similar to the reaction airwashing means 27A of the system S1 of the fuel cell apparatus shown inFIG. 1, except that washing liquid other than water for removing harmfulsubstance in the reaction air is contained in the washing liquid tank27-2, and a trace of harmful substances contained in the air is removedby introducing air in the washing liquid tank 27-2.

Consequently, the reaction air washing means 27C has the same functionaleffects as the reaction air washing means 27A of the system S1 of thefuel cell apparatus shown in FIG. 1 and moreover, harmful substancesthat can not be washed out with water can be eliminated by making airinto contact and mixed with washing liquid other than water in thewashing liquid tank 27-2 containing the washing liquid other than water.

FIG. 4 is a composition diagram showing a fourth embodiment of the fuelcell apparatus of the present invention. The fuel cell 6 of a system S4of the fuel cell apparatus is similar to the reaction air washing means27B, 27C of the system S2, S3 of the fuel cell apparatus shown in FIG. 2and FIG. 3, except that it comprises a reaction air washing means 27Dcomposed by coupling the washing liquid tank 27-1 shown in FIG. 2 andthe washing liquid tank 27-2 shown in FIG. 3 in series.

Consequently, the reaction air washing means 27D has the same functionaleffects as the reaction air washing means 27B, 27C shown in FIG. 2, FIG.3 and moreover, as the trace of harmful substances contained in the air(the atmosphere air) that can not be washed out with water is eliminatedfirst in the washing liquid tank 27-2 containing washing liquid otherthan water in the first stage and then, in the second stage, the washingliquid tank 27-1 containing a water is supplied with the air through thepassage, harmful substances are removed sufficiently by washing againwith the water, the air from which harmful substances are removedsufficiently is supplied to the water tank 21 and humidified, and theoxidant pole 6 b of the fuel cell 6 is supplied with humidified air asreaction water, the alteration of electrolyte based on the chemicalreaction between harmful substance and electrolyte and the decrease ofoxygen absorbing ability of the electrode catalyst can further beprevented, and the decrease of cell characteristics caused by them canbe avoided.

FIG. 5 is a composition diagram showing a fifth embodiment of the fuelcell apparatus of the present invention. The system S5 of the fuel cellapparatus is similar to the system S1 of the fuel cell apparatus shownin FIG. 1, except that the water tank 21 is supplied with water by watertreating city water by the water treatment apparatus 37 through thepassage 38, air (the atmosphere air) is taken by a pump 30 through afilter 29 and supplied directly to the water tank 21 through an airsupply passage 31, and a means for discharging periodically water aswashing liquid contained in the water tank 21 is disposed.

The water tank 21 is supplied with a predetermined quantity of water(for example, pure water) by water treating city water by the watertreatment apparatus 37 through the passage, and maintained to apredetermined level.

On the other hand, air (the atmosphere air) taken by the pump 30 andfrom which dust or the like are remove through the filter 29 is suppliedto the water tank 21 through the air supply passage 31. Then, the watersupplied to the water tank 21 is made into contact, mixed and washedsufficiently with the water for removing harmful substances.

Thus, air from which a trace of harmful substances contained in the airis eliminated, and humidified can be supplied to the oxidant pole 6 b ofthe fuel cell 6 as reaction air.

Water contained in the water tank 21 used for washing the air isdischarged periodically by opening the on-off valve 36 for waterdischarge automatically or manually.

As it is so configured to supply the water tank 21 with fresh water,after the discharge, harmful substances can be removed alwayscontinuously and easily in the water tank 21, and air containing harmfulsubstance is limited and prevented from being supplied to the oxidantpole 6 b of the fuel cell 6 through the water tank 21.

Though water is used as washing liquid in the water tank 21, for theaforementioned embodiment shown in FIG. 5, the washing liquid is notlimited to the water, but the other washing liquids may also be used,and for example, organic compounds may be used.

The description of the aforementioned embodiments intends to explain thepresent invention and not to restrict the invention described in claims,nor reduce the scope. Besides, the composition of respective componentsof the present invention is not limited to the aforementionedembodiments, but can modified in a variety of ways without departingfrom the technical scope described in claims.

For example, the present invention is not limited to the fuel cellapparatus having a fuel cell using a solid polymer electrolyte film suchas solid polymer type fuel cell or direct methanol type fuel cell, butit can also be applied to a fuel cell apparatus using the other fuelcells such as phosphoric acid type.

The fuel cell apparatus of claim 1, wherein the oxidant pole is suppliedwith air washed with washing liquid in the washing liquid tank disposedin the air supply passage, and the washing liquid is replaced, allows tosupply the oxidant pole with always clean air not containing NOx, SOx,cyanides, sulfates, aromatics, ammonium, or the other harmful substancesexerting bad effects on the cell characteristics and has an remarkableeffect of improving the reliability, life and durability, as thealteration of electrolyte based on the chemical reaction between harmfulsubstance and electrolyte and the decrease of oxygen absorbing abilityof the electrode catalyst can be prevented, and the decrease of cellcharacteristics caused by them can be avoided.

The fuel cell apparatus of claim 2 allows to remove impurities in theair by using water or washing liquid of organic compound as washingliquid.

The fuel cell apparatus allows to plan a further air purification byusing a plurality of stages of washing liquid tank for cleaning the air,and furthermore, allows to remove a variety of impurities, particularly,by a combination of washing liquid tank using water and a washing liquidtank using washing liquid of organic compound and, in addition, in caseof using such a plurality of stages of washing liquid tank, thereplacement of washing liquid becomes effective only by executing atleast for the washing liquid tank arranged upstream.

The fuel cell apparatus has a remarkable effect of allowing to supplyeasily the lower washing liquid tank with water from the upper washingliquid tank, as a plurality of washing liquid tanks reserving the samewashing liquid are disposed differently from each other in the liquidlevel, and the lower washing liquid tank is supplied with washing liquidfrom an upper washing liquid tank by the level difference.

The fuel cell apparatus has a remarkable effect of allowing to removeharmful substances more effectively, as the washing liquid tank issupplied with a water from which dust or the other impurities areremoved, a water from which harmful substances are eliminated, or a purewater obtained by the water treatment.

The fuel cell apparatus wherein the oxidant pole is supplied with airwashed with washing liquid in the washing liquid tank disposed in theair supply passage, and the washing liquid is replaced, allows to supplythe oxidant pole with always clean air not containing NOx, SOx,cyanides, sulfates, aromatics, ammonium, or the other harmful substancesexerting bad effects on the cell characteristics and has an remarkableeffect of improving the reliability, life and durability, as thealteration of electrolyte based on the chemical reaction between harmfulsubstance and electrolyte and the decrease of oxygen absorbing abilityof the electrode catalyst can be prevented, and the decrease of cellcharacteristics caused by them can be avoided and furthermore, coolingthe water tank using the cooling water of the water tank, and also beingable to be used for humidification of reaction air to be supplied to theoxidant pole, because it comprises a water tank for reserving coolingwater of the fuel cell.

The fuel cell apparatus wherein the means for replacing washing liquidis operated every fixed time has a remarkable effect of always supplyingthe fuel cell with a clean air free from harmful substances exerting badeffects to the cell characteristics by replacing the washing liquidevery fixed time.

The fuel cell apparatus wherein the means for replacing washing liquidis operated according to the dirtiness of washing liquid has aremarkable effect of always supplying the fuel cell with a clean airfree from harmful substances exerting bad effects to the cellcharacteristics by replacing the washing liquid before the dirt ofwashing liquid attains a bad level, and further improving thereliability.

The fuel cell apparatus comprising a means for supplying the washingtank with water of the water tank has a remarkable effect of usingeffectively water of the water tank, and allowing to intend cost down,miniaturization, or the others.

The fuel cell apparatus wherein the air is supplied to the oxidant pole,after impurities in the air in the washing liquid tank is removed, andthe air is humidified in the water tank, has a remarkable effect ofalways supplying the fuel cell with a clean air free from harmfulsubstances exerting bad effects to the cell characteristics andfurthermore improving ion electric conductivity by humidifying the solidpolymer electrolyte film with moisture contained in the air to besupplied to the oxidant pole.

Industrial Applicability

The fuel cell apparatus of the present invention, comprising a fuel cellfor generating electricity by supplying a fuel pole with fuel gas and anoxidant pole with air, a washing liquid tank, disposed in a supplypassage of the air, for reserving washing liquid, and a means forreplacing the washing liquid reserved in the washing liquid tank, andsupplying the oxidant pole with air washed with the washing liquid, andreplacing the washing liquid periodically, allows to supply the oxidantpole with always clean air. As it can supply the oxidant pole with cleanreaction air not containing harmful substances exerting bad effects onthe cell characteristics, prevent the alteration of electrolyte based onthe chemical reaction between harmful substance and electrolyte, andprovide a fuel cell apparatus of high reliability, long life and highdurability, its industrial utility is extremely important.

1. A fuel cell apparatus, comprising; a fuel cell for generatingelectricity by supplying a fuel pole with fuel gas and an oxidant polewith air, a washing liquid tank, disposed in a supply passage of theair, for reserving washing liquid, and a means for periodicallyreplacing the washing liquid reserved in said washing liquid tank,wherein said washing liquid tanks are disposed in plurality in series onthe air supply passage, and comprises a means for replacing periodicallyat least the washing liquid reserved in the washing liquid tank arrangedupstream.
 2. The fuel cell apparatus according to claim 1, wherein aplurality of washing liquid tanks reserving the same washing liquid aredisposed differently from each other in the liquid level, and a lowerwashing liquid tank is supplied with the washing liquid from an upperwashing liquid tank by the level difference.